68 lines
2.8 KiB
C
68 lines
2.8 KiB
C
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/* (C) 2008 Jean-Marc Valin, CSIRO
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*/
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/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of the Xiph.org Foundation nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/* This is a simple MDCT implementation that uses a N/4 complex FFT
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to do most of the work. It should be relatively straightforward to
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plug in pretty much and FFT here.
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This replaces the Vorbis FFT (and uses the exact same API), which
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was a bit too messy and that was ending up duplicating code
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(might as well use the same FFT everywhere).
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The algorithm is similar to (and inspired from) Fabrice Bellard's
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MDCT implementation in FFMPEG, but has differences in signs, ordering
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and scaling in many places.
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*/
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#ifndef MDCT_H
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#define MDCT_H
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#include "kiss_fft.h"
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#include "arch.h"
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typedef struct {
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int n;
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kiss_fft_cfg kfft;
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kiss_twiddle_scalar * __restrict trig;
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} mdct_lookup;
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void mdct_init(mdct_lookup *l,int N);
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void mdct_clear(mdct_lookup *l);
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/** Compute a forward MDCT and scale by 4/N */
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void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out, const celt_word16_t *window, int overlap);
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/** Compute a backward MDCT (no scaling) and performs weighted overlap-add
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(scales implicitly by 1/2) */
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void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out, const celt_word16_t * __restrict window, int overlap);
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#endif
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